Cartilage treatment probe

ABSTRACT

An electrosurgical instrument for ablating cartilage while limiting collateral damage includes a non-conducting head with a small electrically conductive surface. The head of the instrument is coupled to a shaft by a flexible portion. The flexible portion biases the electrically conductive surface towards a tissue surface. The head is pivotably coupled to the shaft such that the electrically conductive surface is oriented substantially parallel to the tissue surface as the head slides across the tissue surface. A method of performing electrosurgery includes positioning the electrically conductive surface adjacent to the tissue surface, and sliding the shaft across the tissue surface with the head pivoting such that the electrically conductive surface is oriented substantially parallel to the tissue surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/766,894, filed Jan. 30, 2004, titled “Cartilage Treatment Probe,”which claims priority under 35 U.S.C. §119(e) to U.S. Provisional PatentApplication Ser. No. 60/443,840, filed on Jan. 31, 2003, titled“Cartilage Treatment Probe.” The contents of the prior applications arehereby incorporated by reference in their entirety.

TECHNICAL FIELD

This disclosure relates generally to a probe for treating cartilage.

BACKGROUND

Articular cartilage is prone to diseases, such as chondromalacia andosteoarthritis, which result in fibrillation, or fraying, of thecartilage. Damaged cartilage is not as effective in maintainingstiffness and resilience, and in minimizing stress due to load. Thediseases tend to degenerate over time if left untreated, and can resultin the total loss of articular cartilage in the joint. It is desirableto treat these diseases to re-establish a smooth, stable articularsurface.

SUMMARY

Radio-frequency energy delivered through a low-mass or low-surface areaelectrode can be used to rapidly debride cartilage fibrillations andsmooth and/or seal the cartilage surface while producing minimalcollateral damage, which typically occurs in the form of chondrocytedeath and/or the excess removal of healthy tissue. Chondrocytes are thecells that maintain cartilage viability and growth. These cells arekilled when exposed to temperatures of 45° C. or more. After death,chondrocytes tend not to regenerate.

The probe may include one or more of the following features. Anon-conducting bumper that limits removal of excess amounts ofcartilage; a flexible tip that facilitates optimum articular surfacecontact by the electrode over complex geometries, providing goodaccessibility to the tissue site of interest and safe operation; andsoftware controls are designed such that the device operates in theablative mode and effects of poor technique or misuse are minimized. Theprobe preferably operates in an ablative mode, with most of the RFenergy involved in debriding and smoothing and little excess energyavailable to heat collateral tissue and cause excessive chondrocytedeath.

The probe includes, e.g., a shaft and an electrically conductivesurface. In embodiments, the electrically conductive surface ispivotably coupled, directly or indirectly, to the shaft, and is on ahead or bumper at a distal portion of the shaft. The instrument caninclude a flexible portion, which is part of, or attached to, the shaft.

According to an aspect of the invention, an electrosurgical instrumentincludes a shaft, a flexible portion, and a head coupled to the shaftthrough the flexible portion. The head also is pivotably coupled to theflexible portion. The head includes an electrically conductive surfaceand the flexible portion is configured to bias the electricallyconductive surface towards a tissue surface.

Embodiments of this aspect may include one or more of the followingfeatures.

The flexible portion includes a nitinol wire, a nitinol tube, a spring,or a distal portion of the shaft. The distal portion is corrugated, orhas a radial cross section similar to a radial cross section of theremainder of the shaft. The flexible portion is configured to flex in atleast one direction and the head is configured to pivot about an axissubstantially perpendicular to that direction. The head also isconfigured to pivot in three dimensions about the flexible portion,wherein the head and the flexible portion are coupled by aball-and-socket joint.

The head includes a slot about which the head is configured to pivot.The slot is a transverse slot pivotably receiving the flexible portionor pivotably receiving a wire, which may be rigid, coupled to theflexible portion. Alternatively, a living hinge is disposed between thehead and the flexible portion. The living hinge is adjacent to andconnects the head and the flexible portion, and the living hingeincludes a section that is thinner than portions of the head and theflexible portion that are adjacent to the living hinge.

The head includes a non-conductive surface arranged relative to theelectrically conductive surface to limit penetration of the electricallyconductive surface into the tissue surface. The non-conductive surfaceis substantially planar. The electrically conductive surface projectsfrom the non-conductive surface or is substantially flush with thenon-conductive surface. The electrically conductive surface has asmaller surface area than the non-conductive surface.

The head includes an electrode that includes the electrically conductivesurface. The electrode has a T-shape or an L-shape. The instrumentfurther includes a return electrode, wherein the electrically conductivesurface and the return electrode are configured to be coupled toopposite poles of an electrosurgical generator.

In illustrated embodiments, the head includes a first portion and asecond portion. The first portion includes a projection and the secondportion defines a hole that receives the projection. The projection isdeformed to secure the projection in the hole. The first portionincludes a groove and the second portion includes a ridge aligned withthe groove. In a particular embodiment, the head has a substantiallyparallelepiped shape.

In another particular embodiment, the instrument further includes asheath coupled to the shaft and moveable to at least partially cover theflexible portion and the head.

According to another aspect, a method of performing electrosurgeryincludes positioning an electrically conductive surface of a head of aninstrument adjacent to a tissue surface. The head is pivotable relativeto a shaft of the instrument. The method includes moving the shaftrelative to the tissue surface with the head pivoting such that theelectrically conductive surface is oriented substantially parallel tothe tissue surface. The method may include biasing the electricallyconductive surface towards the tissue surface using a flexible portionof the instrument.

According to another aspect, an electrosurgical instrument includes ashaft and a head that is coupled to the shaft. The head includes anelectrically conductive surface. The head is pivotable relative to theshaft such that the electrically conductive surface is orientedsubstantially parallel to the tissue surface as the head moves acrossthe tissue surface.

According to another aspect, an electrosurgical instrument includes ashaft and a head that is coupled to the shaft and pivotable relative tothe shaft. The head includes an electrically conductive portion, fortreating tissue, positioned at only one side of the head.

According to another aspect, an electrosurgical instrument includes ashaft and a head that is coupled to the shaft and that includes anelectrically conductive surface. The head is configured to pivotrelative to the shaft and to slide across a tissue surface as theelectrically conductive surface is moved across the tissue surface.

According to another aspect, a method of performing electrosurgeryincludes positioning an electrically conductive surface of a head of aninstrument adjacent to a tissue surface. The head is pivotably coupledto a shaft. The method includes sliding the head across the tissuesurface. The head pivots relative to the shaft to facilitate thesliding.

According to another aspect, a method of treating chondromalaciaincludes positioning an electrically conductive surface of a head of aninstrument adjacent to a cartilage surface. The head is pivotablerelative to a shaft of the instrument. The method includes moving theshaft relative to the cartilage surface. The head pivots relative to thecartilage surface. The method includes applying electrical energy to theelectrically conductive surface to treat chondromalacia.

According to another aspect, an electrosurgical instrument includes ashaft, a resiliently flexible portion, and a head. The head is pivotablycoupled to the resiliently flexible portion and the head is coupled tothe shaft through the resiliently flexible portion. The head includes asubstantially planar tissue contact surface including an electricallyconductive portion.

Embodiments of this aspect may include one or more of the followingfeatures. The shaft defines a longitudinal axis and the head is offsetfrom the axis. The resiliently flexible portion includes a distalportion of the shaft. The substantially planar contact surface includesa non-conductive portion. The non-conductive portion has a largersurface area than the electrically conductive portion. An electricallead is coupled to the electrically conductive portion.

According to another aspect, an electrosurgical instrument includes aconducting mean for applying energy to a region of tissue. Theinstrument includes a flexing means coupled to the conducting means forbiasing the conducting means towards the region of tissue. Theinstrument includes a pivoting means for pivoting the conducting meansrelative to the flexing means.

According to another aspect, an electrosurgical instrument includes ashaft, a conducting means for applying energy to a tissue surface, and apivoting means for pivoting the conducting means relative to the shaft.

Embodiments of this aspect may include one or more of the followingfeatures.

The electrosurgical instrument includes flexing means coupled to theconducting means for biasing the conducting means towards the tissuesurface. The flexing means includes a flexible portion. The flexibleportion is configured to bias the conductive surface towards the tissuesurface. The conducting means includes an electrically conductivesurface. The pivoting means includes a head pivotably coupled to theflexing means, and the head includes the electrically conductivesurface.

The electrosurgical instrument includes a resiliently flexible portion.The conducting means includes an electrically conductive surface. Thepivoting means includes a head coupled to the shaft through theresiliently flexible portion and pivotably coupled to the resilientlyflexible portion. The head includes a substantially planar tissuecontact surface including the electrically conductive portion.

The conducting means includes an electrically conductive surface. Thepivoting means includes a head coupled to the shaft and including theelectrically conductive surface. The head is pivotable relative to theshaft such that the electrically conductive surface is orientedsubstantially parallel to the tissue surface as the head moves acrossthe tissue surface.

The pivoting means includes a head that is coupled to the shaft and thatis pivotable relative to the shaft. The conducting means includes anelectrically conductive surface included on, and positioned at only oneside of, the head.

The conducting means includes an electrically conductive surface. Thepivoting means includes a head coupled to the shaft and including theelectrically conductive surface. The head is configured to pivotrelative to the shaft and to slide across the tissue surface as theelectrically conductive surface is moved across the tissue surface.

According to another aspect, a method of performing electrosurgeryincludes positioning an electrically conductive surface of a head of aninstrument adjacent to a tissue surface. The head is pivotable relativeto a shaft of the instrument.

Embodiments of this aspect may include one or more of the followingfeatures. The method includes moving the shaft relative to the tissuesurface with the head pivoting such that the electrically conductivesurface is oriented substantially parallel to the tissue surface. Themethod includes sliding the head across the tissue surface. The headpivots relative to the shaft to facilitate the sliding. The methodincludes moving the shaft relative to a cartilage surface of the tissuesurface. The head pivots relative to the cartilage surface. The methodfurther includes applying electrical energy to the electricallyconductive surface to treat chondromalacia.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of an embodiment of a cartilage treatment probe;

FIG. 2 is a side view of an active tip of the probe shown in FIG. 1;

FIG. 3 is a top view of the tip shown in FIG. 1;

FIG. 4 is a bottom view of the tip shown in FIG. 1;

FIG. 5 is an end view of the tip shown in FIG. 1;

FIGS. 6 and 7 show the tip of the probe shown in FIG. 1 positioned on anarticular surface;

FIG. 8 shows the tip of the probe shown in FIG. 1 with an outer sheathof the probe advanced over the tip;

FIG. 9 is a side view of a second embodiment of a cartilage treatmentprobe;

FIG. 10 is a side view of a third embodiment of a cartilage treatmentprobe;

FIG. 11 is a top view of an upper bumper portion of the cartilagetreatment probe of FIG. 10;

FIG. 12 is a side view of the upper bumper portion of the cartilagetreatment probe of FIG. 10;

FIG. 13 is a front end view of the upper bumper portion of the cartilagetreatment probe of FIG. 10;

FIG. 14 is a top view of a lower bumper portion of the cartilagetreatment probe of FIG. 10;

FIG. 15 is a side view of the lower bumper portion of the cartilagetreatment probe of FIG. 10;

FIG. 16 is a front end view of the lower bumper portion of the cartilagetreatment probe of FIG. 10;

FIG. 17 is a side view of a fourth embodiment of a cartilage treatmentprobe;

FIG. 18 is an exploded perspective view of the cartilage treatment probeof FIG. 17;

FIG. 19 is a side view of a fifth embodiment of a cartilage treatmentprobe;

FIG. 20 is a top view of the cartilage treatment probe shown in FIG. 19;

FIG. 21 is a side view of a sixth embodiment of a cartilage treatmentprobe.

DETAILED DESCRIPTION

Referring to FIG. 1, a cartilage treatment probe 10 includes a proximalsection 12 for attachment to a radiofrequency power supply, a shaft 14,and a distal, active tip 16. Shaft 14 is formed from a stainless steeltube 17 (see FIG. 3) covered with insulation, e.g., heat shrink tubing,which is surrounded by a sheath 18.

Referring to FIGS. 2 and 3, tip 16 extends from a distal end 20 of shaft14. Tip 16 includes a bumper, or head, 22 formed from one or moreelectrically insulating materials, e.g., an electrically insulatingceramic or tetrafluorethylene (TFE) material, that has a generallyplanar tissue contacting surface 22 a. Bumper 22 defines a transverseslot 24 for pivotably coupling bumper 22 to a flexible portion, i.e., anitinol wire form 26.

As shown in FIG. 4, nitinol wire form 26 loosely resides in transverseslot 24. Wire form 26 is in a super-elastic state, as explained below.Wire form 26 is held in place by a retainer disk 28 that is glued tobumper 22 or snaps into bumper 22, allowing bumper 22 to pivot freelyabout nitinol wire form 26. The proximal ends 30, 32 of wire form 26 areattached to distal end 20 of shaft 14, such as by being inserted intodistal end 20 of shaft 14 and crimped to stainless steel tube 17. Bumper22 pivots about an axis defined by wire form 26 that is substantiallyperpendicular to the longitudinal axis of shaft 14, although thisorientation can be varied. Nitinol wire form 26 is arranged so that, ina relaxed state, bumper 22 is offset from a longitudinal axis of shaft14 by a distance D and by an angle α, as shown in FIG. 2, to facilitateaccessing tissue with bumper 22.

Referring again to FIG. 2, bumper 22 has a height H in the range ofabout 0.05 to 0.15 inches, preferably about 0.09 inches, a width W inthe range of about 0.10 to 0.19 inches, preferably about 0.14 inches,and a length L in the range of about 0.10 to 0.30 inches, preferablyabout 0.20 inches. Bumper 22 is offset from the longitudinal axis ofshaft 14 distance D in the range of about 0.01 to 0.40 inches,preferably about 0.15 inches. The distance D is measured from thelongitudinal axis of shaft 14 to a line parallel to the longitudinalaxis that intersects transverse slot 24, as shown in FIG. 2. The angle αis approximately 30 degrees. Angle α can range from about 0 to 45 atleast about degrees on either side of the longitudinal axis.

Referring again to FIGS. 3 and 4, tip 16 includes a “T” shaped electrode34 having a stem 38 and a top 44. Electrode 34 is made from anelectrically conductive material, e.g., stainless steel flat stock or awire form. Bumper 22 defines a hole 36 and stem 38 of the “T” is locatedin hole 36. Soldered, or otherwise attached, to the end of stem 38 is apower lead 40. Power lead 40 is a thin flexible conductor strip chosenfor its flexibility and low profile. Proximal of tip 16, power lead 40is positioned between tube 17 and the heat shrink tubing surroundingtube 17, and extends to the proximal end of probe 10 for connection to acable running to the power supply. Bumper 22 also defines a cut-out 42in tissue contacting surface 22 a, in which top 44 of the “T” resides toform an electrically conductive, active portion 46 of the electrode, forapplying energy to tissue. Top 44, which forms an electricallyconductive surface of portion 46, is substantially planar but othersurface geometries can be used.

Referring to FIG. 5, top 44 of the “T” is positioned in bumper 22 suchthat electrically conductive portion 46 is flush with tissue contactingsurface 22 a or extends out from tissue contacting surface 22 a by about0.0003 to 0.004 inches. Portion 46 also can be recessed in tissuecontacting surface 22 a by about 0.0003 to 0.004 inches. The active,electrically conductive portion 46 of the electrode preferably has asmall surface area in the range of about 0.0002 to 0.0065 square inches,preferably about 0.0009 to 0.0036 square inches, more preferably in therange of about 0.0016 to 0.0021 square inches, and most preferably about0.0018 square inches. The surface area of portion 46 is substantiallysmaller than the surface area of tissue contacting surface 22 a, whichcan be, for example, in the range of about 0.01 to 0.057 square inches,preferably about 0.028 square inches. Bumper 22 acts as a physicalbarrier to limit the depth of penetration of electrode 34 into thetissue. Bumper 22 also masks portions of electrode 34, except forportion 46, to limit the direction of current flow from electrode 34.Power lead 40 and stem 38 of electrode 34 are surrounded by aninsulating material (not shown) such that portion 46 is exposed only ontissue contacting surface 22 a of bumper 22.

Referring to FIGS. 6 and 7, in use, probe 10 can be positioned adjacentto a tissue surface 50 to be treated, so that the electricallyconductive surface of portion 46 is substantially parallel to tissuesurface 50. Radio frequency power is delivered to portion 46 from aradio frequency generator (not shown), such as, for example, the Vulcan®generator sold by Smith & Nephew, Inc, Andover, Mass. As probe 10 ismoved across tissue surface 50, bumper 22 pivots freely about nitinolwire form 26 to facilitate tissue contacting surface 22 a sliding acrosstissue surface 50 and the surface of electrically conductive portion 46remaining substantially parallel to tissue surface 50. Nitinol wire form26, which is extremely flexible in multiple directions, provides tip 16with a range of flexibility relative to shaft 14 such that bumper 22 andthe active, electrically conductive portion 46 of electrode 34 remainssubstantially in contact with articular tissue surface 50 whiletraveling over complex geometries. The resistance to deformation of thenitinol in its superelastic state is constant, providing a spring actionthat helps bumper 22 and the electrically conductive surface of portion46 follow the curvature of tissue surface 50 while maintaining acontrolled, approximately uniform contact pressure of the bumper 22 andelectrode 34 against articular cartilage surface 50 over complexgeometries as nitinol wire 26 is deflected. The spring action of nitinolwire 26 also biases bumper 22 towards tissue surface 50 when probe 10 ispressed towards tissue surface 50. Nitinol wire 26 can be referred to asa spring, and other springs or spring materials, such as, for example,stainless steel spring wire, can be used.

Referring to FIG. 8, sheath 18 can be slid forward relative to stainlesssteel tube 17 to cover tip 16 to provide temporary rigidity to flexibletip 16 for insertion into and removal from the joint capsule. Sheath 18includes ribs 52 (FIG. 1) that facilitate grasping of sheath 18 toextend and retract sheath 18. When covering tip 16, sheath 18 alsoprotects tip 16 and limits catching of tip 16 on tissue.

Power is preferably delivered to probe 10 under the control of animpedance feedback loop to maintain the probe in an ablative mode. Inaddition, since the impedance rises when the probe is not being movedacross tissue, impedance feedback can be used to recognize when theprobe is not being moved and controls can be used to turn off the powerand/or sound an alarm. Probe 10 also can include one or more temperaturesensors, such as a thermistor mounted in tip 16, to monitor thetemperature at or near tip 16. The temperature sensors and the powergenerator can be coupled by a feedback control system that regulates theamount of energy delivered to the probe based on the temperature at ornear tip 16, in order to control the temperature of tissue surface 50.These control systems can be implemented, for example, in software.

The use of a small surface area electrode allows the probe to functionin an ablative mode at low power and provides for low thermalpenetration into the tissue such that the extent of cell death can bemaintained at preferably less than about 200 microns. This results insurface smoothing of the cartilage of the articular surface with minimaltissue removal and cell death. The use of probe 10 is indicated, e.g.,for chondromalacia lesions Outerbridge System Grades II and III, as wellas for stabilizing the rim of Grade IV lesions. It is believed that anadditional benefit of the use of probe 10 is the sealing of articularsurfaces to stop or slow down the degradation process of the cartilage.

Probe 10 has been shown as a monopolar device. A monopolar device hascertain advantages over a bipolar device, such as the smaller size ofthe monopolar device facilitating access to small joint spaces, and thepresence of only one electrode in the joint space so the user does nothave to be concerned with inadvertent contact of a return electrode withtissue. However, the probe can be bipolar by incorporating a returnelectrode on the shaft or elsewhere on the probe, as discussed withrespect to FIG. 9 below.

Stainless steel tube 17 need not define a lumen along its entire length,but need only be able to receive ends 30 and 32 of the nitinol wire 26to attach ends 30 and 32 to the distal end 20 of tube 17. For example,tube 17 can be solid along the majority of its length, providingadditional rigidity to the probe, and include one or two openings atdistal end 20 of tube 17 into which ends 30 and 32 of nitinol wire 26are inserted.

Referring to FIG. 9, an alternate embodiment of a cartilage treatmentprobe 900 includes an active tip 916 that attaches to distal end 20 ofshaft 14, as discussed above. Active tip 916 includes a bumper, or head,922, having a tissue contacting surface 922 a. Tissue contacting surface922 a includes an electrically conductive surface 935 of an activeelectrode 930 for applying energy to tissue. Electrically conductivesurface 935 is rounded and extends out from tissue contacting surface922 a a small amount, such as approximately 0.0003 to 0.004 inches.Alternatively, electrically conductive surface 935 can be flush with orrecessed in tissue contacting surface 922 a. Electrically conductivesurface 935 has a surface area substantially smaller than tissuecontacting surface 922 a, as discussed above.

Bumper 922 defines a transverse slot 924 that receives a nitinol wire940, or more generally a flexible member, for pivotably coupling bumper922 to shaft 14, as discussed above. A portion 942 of nitinol wire 940is located in slot 924 and is surrounded by a sleeve 944 to facilitatepivoting of bumper 922 about nitinol wire 940. Slot 924 is closed offwith a non-conductive filler material 928, which can be the same as ordifferent from the material of bumper 922, in order to hold nitinol wire940 in slot 924, while allowing bumper 922 to pivot about nitinol wire940.

Active electrode 930 is L-shaped and bumper 922 defines a correspondingL-shaped aperture 925 for receiving active electrode 930. Also withinL-shaped aperture 925, a distal portion 952 of an active power lead 950is soldered, or otherwise attached, to a top surface 934 of activeelectrode 930. Distal portion 952 of active power lead 950 and topsurface 934 of active electrode 930 are closed off by an electricallyinsulating filler 954, which is the same or a different material thanbumper 922. Accordingly, active electrode 930 is exposed only atelectrically conductive surface 935, and bumper 922 includes anelectrically conductive portion for treating tissue positioned at onlyone side (tissue contacting surface 922 a) of bumper 922. It should beunderstood that electrode 930 and aperture 925 can have any othersuitable geometry that allows electrode 930 to be mounted to bumper 922.

Shaft 14 also includes an electrically conductive surface of a returnelectrode 960 coupled to a return power lead 962. Return electrode 960is shown flush with the outer surface of shaft 14, but return electrode960 can project from or be recessed in shaft 14. For example, shaft 14can be formed by a stainless steel tube covered with insulation, andreturn electrode 960 can be disposed over the insulation. Another layerof insulation can be disposed over a portion of return electrode 960and/or return power lead 962. Return electrode 960 and/or return powerlead 962 also can be formed from the stainless steel tube.

Active power lead 950 and return power lead 962 are coupled to oppositepoles of a bipolar electrosurgical generator (not shown), such as theaforementioned Vulcan® generator. Thus, probe 900 operates in a bipolarmode with current mainly flowing from electrically conductive surface935, through or around the tissue surface, to return electrode 960. Itshould be understood that return electrode can be located on anotherpart of probe 10, such as, for example, on bumper 22 or on nitinol wire940.

Referring to FIG. 10, an alternative embodiment of a cartilage treatmentprobe 1000 includes an active tip 1016 that attaches to distal end 20 ofshaft 14, as discussed above. Active tip 1016 includes a bumper, orhead, 1022 having a tissue contacting surface 1022 a. Tissue contactingsurface 1022 a of bumper 1022 includes an electrically conductivesurface 1035 of an electrode 1030 for applying energy to tissue.Electrically conductive surface 1035 is rounded and is recessed withintissue contacting surface 1022 a a small amount, such as approximately0.0003 to 0.004 inches. Alternatively, electrically conductive surface1035 can be flush with or extend from tissue contacting surface 1022 a,as discussed above. Electrically conductive surface 1035 also has asurface area substantially smaller than a surface area of tissuecontacting surface 1022 a, as discussed above.

Bumper 1022 defines a transverse slot 1024 that receives a flexibleportion 1040, which is a nitinol wire, for pivotably coupling bumper1022 to shaft 14, as discussed above. Bumper 1022 includes an upperbumper portion 1060 (FIGS. 11-13) and a lower bumper portion 1070 (FIGS.14-16). Upper bumper portion 1060 and lower bumper portion 1070 are madeof the same or different non-conductive materials, such as ceramic orTFE.

Referring to FIGS. 10-13, upper bumper portion 1060 includes transverseslot 1024, an upper mating surface 1062, and a cylindrical projection1064 projecting down from upper mating surface 1062. Upper bumperportion 1060 also includes an upper electrode receiving aperture 1066configured to receive a top portion 1034 of L-shaped electrode 1030 andan end portion 1052 of a power lead 1050. As shown in FIGS. 10 and 12,upper electrode receiving aperture 1066 includes a rectangular portion1067 intersecting upper mating surface 1062 and a tapered portion 1068intersecting an upper surface 1022 b of bumper 1022.

Referring to FIGS. 10 and 14-16, lower bumper portion 1070 includestissue contacting surface 1022 a and a lower mating surface 1072. Lowerbumper portion 1070 also includes a substantially round projectionreceiving hole 1074 for receiving projection 1064 of upper bumperportion 1060. Hole 1074 includes a tapered section 1075 that tapers froma larger diameter at a point near tissue contacting surface 1022 a to asmaller diameter approximately halfway through hole 1074. Hole 1074 alsoincludes a constant diameter section 1076 that extends from the pointhalfway through the hole 1076 to lower mating surface 1072 as discussedbelow. Lower bumper portion 1070 also includes a lower electrodereceiving aperture 1078 for receiving a lower portion 1032 of L-shapedelectrode 1030.

Bumper 1022 is assembled by passing nitinol wire 1040 through slot 1024,seating electrode 1030 as explained below, and aligning upper matingsurface 1062 of upper portion 1060 and lower mating surface 1072 oflower portion 1070 such that projection 1064 passes through projectionreceiving hole 1074. L-shaped electrode 1030 is seated in electrodereceiving apertures 1066 and 1078 such that bottom portion 1032 isseated in lower aperture 1078 and top portion 1034 is seated inrectangular portion 1067 of upper aperture 1066. Bottom portion 1032 ofelectrode 1030 is exposed at tissue contacting surface 1022 a to formelectrically conductive surface 1035. Projection 1064 is heated todeform projection 1064 so that projection 1064 fills tapered section1075 of projection receiving hole 1074 and locks upper bumper portion1060 to lower bumper portion 1070. In doing so, projection 1064 is madeto be flush with tissue contacting surface 1022 a.

End portion 1052 of power lead 1050 passes through tapered portion 1068and into rectangular portion 1067 of upper aperture 1066 and iselectrically connected to electrode 1030 to transmit electrical energyto electrode 1030. The portion of power lead 1050 outside of bumper 1022is covered with an electrically insulating material. When assembled,only electrically conductive surface 1035 of electrode 1030 is exposed,on tissue contacting surface 1022 a of bumper 1022. Power lead 1050 iscoupled to an electrosurgical generator (not shown) for deliveringmonopolar energy to electrically conductive surface 1035.

Referring to FIG. 17, an alternative embodiment of a cartilage treatmentprobe 1700 includes an active tip 1716. Active tip 1716 includes aflexible portion 1740, a bumper, or head, 1722 and a living hinge 1745.Flexible portion 1740 is coupled to distal end 20 of shaft 14 (e.g., asshown in FIG. 1), such as by ultrasonic welding. Flexible portion 1740is resiliently flexible, has a rectangular cross section, and is made ofan elastic or superelastic material, such as plastic. Flexible portion1740 biases bumper 1722, as discussed above.

Bumper 1722 has a tissue contacting surface 1722 a, which includes anelectrically conductive surface 1735 of an L-shaped electrode 1730 forapplying energy to tissue. Electrically conductive surface 1735 isrounded, extends out from tissue contacting surface 1722 a a smallamount and has a surface area substantially smaller than a surface areaof tissue contacting surface 1722 a, as discussed above. Alternatively,electrically conductive surface 1735 can be flush with or recessed intissue contacting surface 1722 a, as discussed above. Electrode 1730 isexposed only at electrically conductive surface 1735 on tissuecontacting surface 1722 a.

Referring to FIGS. 17 and 18, bumper 1722 includes a lower bumperportion 1770 and an upper bumper portion 1760. Lower bumper portion 1770and upper bumper portion 1760 are made of the same or differentnon-conductive materials, such as ceramic or TFE. Lower bumper portion1770 includes a portion of tissue contacting surface 1722 a. Lowerbumper portion 1770 is substantially T-shaped, including a distalportion 1772 and a proximal portion 1773. Projecting laterally fromproximal portion 1773 are lateral ridges 1774 (only one of which isshown). Distal portion 1772 includes an electrode receiving aperture1776 for receiving a bottom portion 1732 of L-shaped electrode 1730.

Upper bumper portion 1760 includes a top wall 1762 and lateral dependingwalls 1764 arranged in a U-shaped configuration when viewed from adistal end of bumper 1722. Each of lateral depending walls 1764terminate has a terminal end 1765 that forms a portion of tissuecontacting surface 1722 a. An interior surface 1761 of each lateraldepending wall 1764 defines a groove 1766 for receiving lateral ridges1774 of lower bumper portion 1770. An interior surface 1763 of top wall1762 and interior surfaces 1761 define a space 1767 for receiving a topportion 1734 of L-shaped electrode 1730.

Bumper 1722 is assembled by inserting bottom portion 1732 of L-shapedelectrode 1730 into aperture 1776 in lower bumper portion 1770. Proximalportion 1773 of lower bumper portion 1770 is inserted into upper bumperportion 1760 so that lateral ridges 1774 are aligned with or fit intogrooves 1766, and top portion 1734 of electrode 1730 is received inspace 1767 defined by interior surfaces 1761 and 1763. Upper bumperportion 1760 and lower bumper portion 1770 are locked together byfriction fit or by other means such as, for example, an adhesive.Assembled bumper 1722 defines a rear opening 1768 configured to receivea power lead (not shown) for attachment to electrode 1730. The remainingspace between electrode 1734 and interior surfaces 1731, 1733 is filledwith a non-conductive material, such as, for example, a ceramic orplastic epoxy.

Bumper 1722 is pivotably coupled to flexible portion 1740 by a livinghinge 1745 disposed between flexible portion 1740 and bumper 1722.Living hinge 1745 includes a thin section 1747 of material integral withflexible portion 1740 and bumper 1722. Thin section 1747 has a thicknessof approximately 0.006 inches, although other dimensions can be used.Flexible portion 1740, upper bumper portion 1760, and living hinge 1745are, for example, molded from a single piece of material. Living hinge1745 is composed of a flexible material, such as, for example,polypropylene or polyethylene, that can flex a large number of timeswithout failure. Living hinge 1745 allows bumper 1722 to pivot relativeto flexible portion 1740, about thin section 1747 as shown by arrow1780.

Referring to FIGS. 19 and 20, an alternate embodiment of a cartilagetreatment probe 1900 includes a shaft 1914, a wire 1980, and a bumper,or head, 1922. Bumper 1922 is indirectly pivotably coupled to a flexibledistal portion 1940 of shaft 1914 by wire 1980. Rather than wire 1980being resiliently flexible, wire 1980 is made from a rigid material,such as stainless steel or plastic, and flexibility is provided byflexible distal portion 1940 of shaft 1914. Flexible distal portion 1940includes a plurality of cutouts 1942 to form a resiliently flexible,corrugated structure. At points between adjacent cutouts 1942, flexibledistal portion 1940, has a radial (or transverse) cross-section that iscircular and that is substantially similar to the radial cross-sectionof the remainder of shaft 1914 proximal of flexible portion 1940.

Bumper 1922 can be, for example, any of bumpers 22, 922, 1022, or 1722and includes an electrode (not shown). Bumper 1922 is pivotably coupledto wire 1980, as discussed above. Wire 1980 is bent so that bumper 1922is offset from a longitudinal axis of shaft 1914 a distance, asdiscussed above, to facilitate accessing a tissue surface with a tissuecontacting surface 1922 a of bumper 1922. Bumper 1922 is generallyparallel to the longitudinal axis, but could be offset by an angle, asdiscussed above, such as by making flexible portion 1940 curved.

Referring to FIG. 21, an alternative embodiment of a cartilage treatmentprobe 2100 includes an active tip 2116 having a bumper, or head, 2122,pivotably coupled to a resiliently flexible portion 2140. Bumper 2122includes an upper bumper portion 2160 and a lower bumper portion 2170,each made of a non-conductive material, such as ceramic or plastic.Upper bumper portion 2160 and lower bumper portion 2170 are joined toone another, for example, by applying an adhesive, brazing, orultrasonic welding, or by one of the other mechanisms discussed above.Flexible portion 2140 is coupled to shaft 14, as discussed above.

Lower bumper portion 2170 includes a tissue contacting surface 2122 aand an L-shaped recess 2172 for receiving an L-shaped electrode 2130, asdiscussed above. L-shaped electrode 2130 includes an electricallyconductive surface 2135 that is flush with tissue contacting surface2122 a. Alternatively, an electrically conductive surface 2135 aprojects from tissue contacting surface 2122 a or an electricallyconductive surface 2135 b is recessed in tissue contacting surface 2122a. Electrically conductive surface 2135 has a surface area substantiallysmaller than tissue contacting surface 2122 a.

Upper bumper portion 2160 defines a recess 2162 and a cavity 2164 thatreceives, in mating relationship, a substantially dome-shaped member2166. Member 2166 is fixedly attached to a distal end of flexible member2140, which is, for example, a nitinol tube. Member 2166 and cavity 2164function like a ball-and-socket joint, allowing bumper 2122 to pivot inthree dimensions about dome shaped member 2166 and flexible member 2140.The three-dimensional pivoting facilitates the sliding of tissuecontacting surface 2122 a across a tissue surface having a complexgeometry while the surface of electrically conductive portion 2135remains substantially parallel to the tissue surface. It should beunderstood that member 2166 and/or cavity 2164 can include stops or canbe shaped differently so as to allow for more or less freedom ofmovement. Further, recess 2162 and cavity 2164 can be positioned inupper bumper portion 2160, for example, more proximally or distally thanshown.

Extending through flexible member 2140 and through an aperture 2155 inmember 2166 is a power lead 2150. A distal end portion 2152 of powerlead 2150 is electrically coupled to L-shaped electrode 2130 to deliverenergy to electrically conductive surface 2135. Distal end portion 2152has sufficient slack to avoid breaking or disconnecting from electrode2130 while bumper 2122 pivots relative to flexible portion 2140. Aproximal end of power lead 2150 is coupled to an electrical energysource (not shown), as discussed above. It should be understood thatpower lead 2150 can be coupled to electrode 2130 without passing throughflexible member 2140.

A number of embodiments have been described. Nevertheless, it will beunderstood that various modifications can be made. For example, thebumper can be directly or indirectly pivotably coupled to the shaft. Inaddition, the bumpers can have any suitable number of sides arranged inany suitable shape, such as a parallelepiped, a triangular prism or ahalf dome with a planar tissue contacting surface. Also, in bumper 1022,projection 1064 can be deformed by a method other than heating, such as,for example, by mechanical deformation. Moreover, upper bumper portion1060 and lower bumper portion 1070 can be joined by another mechanismsuch as friction fit, press fit, or adhesive, or can be made as a singlepiece. Flexible portions 26, 940, and 1040 can be a nitinol wire not ina superelastic state, or can be another elastic or superelasticcomponent, such as a stainless steel or plastic spring. Both the shaftand the nitinol wire can be resiliently flexible to provide additionalflexibility. In addition, the flexing action of the flexible portion canbe in a direction other than that shown. Likewise, the bumper can pivotabout an axis in a different direction than the direction shown. Also,the proximal ends of flexible portions 26, 940, 1040, and 1740 can beattached to the shaft by any suitable means, such as, for example, bycrimping, welding, or press-fitting. The electrodes can be made of anybiocompatible electrically conductive material, such as, for example,stainless steel, tungsten, gold, silver, or platinum. The electricallyconductive surface of an embodiment can, for example, be flush from thetissue contacting surface, project from the tissue contacting surface,or be recessed in the tissue contacting surface. In addition, theelectrically conductive surfaces can be, for example, planar or curved.Moreover, the probe can include more than one electrically conductivesurface and/or return electrode, such as, for example an array ofelectrically conductive surfaces on the bumper. The features describedfor the various embodiments are non-limiting. Further these features canbe combined or interchanged with one another, as well as deleted andsupplemented. Accordingly, these and other embodiments are within thescope of the following claims.

1. A method of treating chondromalacia comprising: positioning anelectrically conductive surface of a head of an instrument adjacent to acartilage surface, the head being pivotable relative to a shaft of theinstrument; moving the shaft relative to the cartilage surface, wherebythe head pivots relative to the cartilage surface; and applyingelectrical energy to the electrically conductive surface to treatchondromalacia.